But what are air bridges, how would they work and could they rescue the summer holiday plans of millions of Britons?

What are air bridges?

The proposal was raised in the House of Commons on Monday by senior Tory MP and chairman of the transport committee, Huw Merriman.

He asked transport secretary Grant Shapps "if he will consider air bridges so that those entering the UK from countries where the infection rate is below the rate of one would not be subject to quarantine?”

Merriman added: "This will boost confidence in aviation travel and target safety where it's most needed."

In theory, the UK could do deals with countries such as France, Germany, Italy and Spain to relax plans to quarantine arriving travellers.

It would mean Britons who travelled abroad could return to the UK without entering quarantine.

What did the government say?

Shapps said the idea of air bridges was one that will be considered by the government.

However, he insisted that planned quarantine measures on travellers to the UK, which will be introduced in June, will initially have a “blanket situation” for other countries.

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Replying to Merriman’s question, Shapps said: "Final details of the quarantine scheme will be released soon, come in early next month.

"It is the case we should consider further improvements – for example, things like air bridges enabling people from other countries who have themselves achieved lower levels of coronavirus infection to come to the country.

"So, those are active discussions but will go beyond what will initially be a blanket situation."

Air bridges are being considered but are not agreed policy, Downing Street said.

The prime minister's official spokesman said: "It's an option under consideration but not agreed government policy."

The quarantine measures will be reviewed every three weeks, the government said. Travellers from Ireland are exempt from the quarantine restrictions.

Where might problems lie with air bridges?

Opposition politicians have been quick to criticise the plan, pointing out that other countries in Europe may not want to open up an air bridge with the UK, given its high COVID-19 death toll and infection rate.

“Travel bubbles can only work where countries work collaboratively on checks and controls.”

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Scottish National Party MP Dr Philippa Whitford pointed to Britain’s infection rate and asked: “Who will want an ‘air bridge’ with UK?”

But Patricia Yates, acting chief executive at Visit Britain, said it was an “interesting” idea and suggested an air bridge with the US could work.

"It would be good to choose the countries that were valuable to us for inbound markets,” she said.

EasyJet planes parked at Gatwick Airport in south London (PA)

“We have an international network, our American regional director is telling us sort of America is ready to go, American business is ready to go. So, possibly, you know, an air bridge between the UK and America might be one that would be valuable to us."

What is the reaction to the quarantine plans?

London mayor Sadiq Khan questioned why the 14-day quarantine on international travellers wasn’t being imposed as soon as possible.

"We have got a number of airports that serve us - Heathrow, Gatwick, City, Stansted and a number of other peripheral ones - but also the Eurostar as well,” he said.

"I think it's really important that anybody coming to our country isolates for at least 14 days. I want them tested as well as soon as they possibly can."

The plans for quarantine restrictions were condemned as "idiotic" and "unimplementable" by Ryanair boss Michael O'Leary.

"You don't have enough police in the UK to implement a two-week lockdown,” he said.

"And what's really worrying is that a two-week lockdown has no medical or scientific basis to it in any event.